This invention relates generally to windshield wiper assemblies and more particularly to wiper assemblies having heated portions.
As will be appreciated, when a vehicle is operated during snow, sleet or other icy/wet conditions, the defroster for the windshield in addition to performing its normal function, warms the outer surface of the windshield. Thus, the ice and snow which fall on the surface are turned to slush and water and are hopefully wiped away with each sweep of the wiper blade, thereby leaving the windshield clear, at least momentarily. However, what usually happens under such conditions is that the wiper blades do not clear the windshield as effectively as desired for safety purposes. Unfortunately, the blades become encrusted with ice, whereupon they are lifted off the glass by the ice. Furthermore, conventional blade holders, with their system of flexible levers or supports, provide perfect attachment points for the slush and water and allow ice to form and, after a very short time, the blade is not only encrusted with ice, but no longer follows the curvature of the windshield for most or all of its length, due to icing of the holder. The vehicle defroster is incapable of heating the blade and its associated mounting means inasmuch as the blade contact with the glass, i.e., the razor thin wiping edge, is of such a small cross-sectional area. Thus, insufficient heat is exchanged from the windshield into the blade to cause the blade to warm sufficiently to thaw the ice formed thereon, let alone heat the blade holder enough to melt the ice formed thereon. In fact, it has been found that the more efficient the defroster system, the more slush and water it creates on the windshield to freeze on and encrust the blades and holders. Thus, heated wiper blades and holders therefor have been suggested in the patent literature.
Various windshield wiper assemblies have been proposed in the patent literature to effect the melting of ice which might accumulate on the blade. Examples of prior art of patented heated wiper blades and/or assemblies are as follows: U.S. Pat. No. 2,677,143 (Blanie); U.S. Pat. No. 2,790,194 (Noreen); U.S. Pat. No. 3,074,096 (Van Hess); U.S. Pat. No. 3,408,678 (Linker); U.S. Pat. No. 33,530,525 (Abel); U.S. Pat. No. 3,619,556 (Deibel et al.); U.S. Pat. No. 4,325,160 (Burgess); U.S. Pat. No. 4,360,941 (Mabie); and U.S. Pat. No. 4,497,083 (Nielsen, Jr. et al.).
While the devices disclosed in the aforementioned patents appear generally suitable for their intended purposes, they nevertheless leave much to be desired from the standpoint of simplicity of construction, and moreover can be greatly improved in terms of effectiveness of operation.
For example, the patent of Nielsen, Jr. et al, U.S. Pat. No. 4,497,083, discloses a heated windshield wiper blade having a resistance wire running along the length of the wiper arm, the blade carrier and the wiper blade to heat the blade and the carrier when it is connected to a vehicle's electrical system. The path through which the resistance wire travels and its various connections is quite complex in order to provide the blade which can be replaced independently of the arm and carrier.
The patent to Mabie, U.S. Pat. No. 4,360,941, discloses a second, rather complex windshield wiper assembly which incorporates a weather protective hood utilizing electrical conductors affixed on the outer wall of the hood and other conductors affixed on the inner wall of the hood to heat the hood and frame to prevent the accumulation of ice.
None of these patents discloses a wiper blade and carrier arm of simple, economical construction wherein the wiper blade can be both easily constructed and easily replaced in the blade arm.